Earlier this week, the Internet was high off the first official confirmation of an exoplanet in a "habitable zone," the area encompassing a star with conditions that could support liquid water. While it's unclear just what makes up Kepler-22b, as this new planet is known, we do know that the thing is 600 light-years away and circling its host star on an orbit comparable, it would seem, to one Earth-year.This is a profound discovery – not yet pack-your-bags worthy, but nonetheless profound given our pathetically limited understanding of the cosmos, its objects and phenomena. And yet, it’s also a reminder about the limits of our understanding of our own planet.In many ways we know more about Earth’s potential twin, and all other inconceivably distant heavenly bodies and events, than we do about what’s happening below the surface right here on Earth. Space is sexy, seemingly vast and empty. The Earth is charred, finite and overcrowded. So it’s unsurprising that even in a time of budgetary belt-tightening, funding for a Mars rover, say, will likely win out over pumping billions of dollar into what would effectively piece together a giant X-ray of our hopeless little rock.But two recent deep-sea mapping expeditions are shining much-needed light across two of Earth’s deepest (and navigable) floors: the Mariana and Tonga trenches. It’s here that some of Earth’s most violent events play out in the dark, remote levels of almost inconceivably punishing habitats.At nearly 11 kilometers down at Challenger Deep, the deepest known point in all the oceans, the western Pacific Ocean’s otherwise inhospitable Mariana Trench is a crevice’s crevice.Don Walsh and Jacques Piccard, manning the research bathyscaphe Trieste, in 1960, are the only two humans who’ve ever been here. Needless to say, it’s not the easiest place to get to, and then as now, only at considerable risk. Mariana is also where a hulking slab of Pacific plate crust grinds down beneath an adjacent slab, the Philippines tectonic plate. Some models have friction from this grinding, or subduction, influencing larger tremors.The Trench is one of the many Meccas of planetary science. But given its conditions, opportunities for research are few. Only now, a team of U.S. scientists are offering the most precise mapping to date of the Challenger Deep.The researchers outfitted a U.S. Navy hydrographic ship with a multibeam echosounder, which charted a stretch of soundings perpendicular to their vessel’s line of travel. They were certain to accurately track each water column’s “sound speed profile.” This a measure of the arc of an echosounding signal firing downward, and is the leading cause of measurement error.The expedition mapped all of Mariana, from Dutton Ridge in the north to where it merges into Yap Trench in the south, all at 100m resolution, Dr. Jim Gardner of the University of New Hampshire’s Center for Coastal & Ocean Mapping, which led the project, tells the BBC. The echosound approach, Gardner adds, was “like mowing the grass.”So, their measure? 10,994 meters, plus or minus 40 meters. The team also managed surveying HMRG Deep, a trench some 200 kilometers east of Challenger, at a depth of 10,809 meters. For scale, keep in mind that both Challenger and HMRG jut far deeper below sea level than Mount Everest towers over it.Not only are these immense depths. They’re the first of their kind. Until now, projected Challenger and HMRG depths have largely been just that – projections. CCOM’s precision study puts the hearts of our oceans, which regulate all life and forces on Earth, squarely under the microscope for the first time, really. But where there’s research there’s quite often money and politics: That first figure, Challenger’s depth, could become a pawn in the global-power game.The expedition, whose findings were just presented at the 2011 American Geophysical Union Fall Meeting, was financed by the U.S. State Department. Apparently the government is curious to know whether an “exclusive economic zone” surrounding Guam and the Northern Mariana Islands, two American territories, could extend beyond 200 nautical miles (370km), its current limit. The land grab could go through should the lay of the newly mapped seafloor meet certain criteria under the U.N. Convention on the Law of the Sea.
A second study that aimed to test the effects of underwater volcano annihilation on tsunamis doesn’t appear to have any political undertones. This was a joint effort of Oxford and Durham universities in partnership with the National Environment Research Council to survey the Tonga Trench region last summer.Images from the study, whose results also were featured at the AGU’s fall summit, illustrate how tectonics are “dragging giant volcanoes into a chasm in the seabed.” It sounds violently awesome, because it is.The Tonga Trench is an active fault line that extends north from New Zealand toward Tonga and Samoa. Second only to Mariana, the Tonga measures in at 10,900m. Situated where the Pacific tectonic plate mashes with the Indo-Australian plate, the trench falls partially in the line of numerous volcanoes strewn and creeping over several thousand kilometers of ocean floor. These volcanoes are part of the Pacific Ring of Fire, and are cruising westward on the Pacific plate at a steady 6cm per year.When they reach the Tonga, they curl in toward a subduction zone. One theory holds that volcanoes actually buffer and ease the subduction process, shearing into blocks as they crumple. Or, maybe this sort of volcanic destruction generates friction between moving plates, thus building tensions that are then released as quakes, then tsunamis.But Oxford researcher and joint project leader Tony Watts claims that the Earth’s swallowing volcanoes here may not trigger point-specific earthquakes as much as previously believed. “When you see the size of these features,” Watts explains, “you’d think they’d cause massive earthquakes and disruption – and that was our starting hypothesis.” But the images, created through sonar in water depths up to 6km, suggest that the volcanoes were quite fractured before entering the Tonga.Such an insight will prove important to our understanding of just what happens after volcanic hunks enter what Walls calls “the system,” which I’ll go out on a limb and guess is geo-code-speak for “the trail to the center of the Earth.”
There are incredible technical and physical challenges that accompany journeys to the trenches of oceanic maw and, maybe someday, down through the tectonic crust and mantle and further on to a mysterious, innermost core.Many of these challenges are insurmountable, at least for the time being. We simply can’t bore much deeper than about 12,400 meters into our continental crust, which is figured to be between 25,000 – 70,000 meters thick. So long as our giant drills, be them on land or at sea, are unable to overcome the crushing pressures that collapse holes in on themselves at great depths, the mantle, and all that may lay beyond, will continue to evade us.I spoke earlier of the allure, the pull of outer space. For a lot of common folk, and all the cats – political figures and burgeoning space travel agencies – with the money to fund either exploratory route, the cosmos can outshine our own planetary studies. But in many ways, the challenges are almost tantamount in the sense that at the end of the day we’re just not good enough, yet. We don’t yet have the (anti?)imaging technologies to “see” dark energy as we can’t yet counteract the crushing forces that only multiply the further down we bore toward our core.Taken together, though, these two projects offer the most comprehensive scan of what are arguably Earth’s most far out ecosystems, alive and still largely-unknown as they are. This week’s Mariana and Tonga results may lay a lot of the groundwork for deeper terrestrial penetration, if we ever dare go there – a risk that’s forever caught up in technological advances in the means of boring down, and the will to fully understand this rock, first.Which is not to disparage a huge milestone from NASA, or anything, especially at a time when that agency continues to be hammered into the shaft of forgotten funding. But setting aside the potentially impenetrable barriers (including funding) to striking the mantle and everything beyond: What does it say that we’re really only just beginning to firmly scratch the surface of this planet?The real question, I think, even if we’re still far off from a time to seriously consider it, is Do we want to light out for Earth’s potential cosmic twin without first giving Earth a thorough overview? If not, if indeed we want to get a better grasp of just what it is we are or are not occupying, are we prepared to swallow the prospect that this would probably only by possible through the whims of competing moneyed players?Reach this writer at brian@motherboard.tv. @thebanderson
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